The need for separation of materials has long been recognized in many diverse fields, including processing of materials such as coal or grain, for example. One of the more commonly utilized devices heretofore developed for processing of such materials is the spiral separator.
The spiral separator is a machine used to process substances containing fractions which differ in shape and/or sliding resistance, and have, therefore, been found to be particularly useful in fields such as coal processing and seed or grain processing.
The spiral separator normally consists of one or more flights spirally wound around a central vertical axis. The substances to be processed are discharged onto the upper end of these flights. Fractions which are round or have differentially less sliding resistance travel at a faster rate then flat fractions or those with greater sliding resistance. As momentum increases, the round fraction, or that fraction with less sliding resistance, rolls off the edge of the spiral flight and is therefore separated since the flat fraction, or the fraction with greater sliding resistance, fails to achieve sufficient momentum to roll or slide off the edge of the spiral flights.
Spiral separators and/or basic operation of such separators are shown, by way of example, in U.S. Pat. Nos. 694,420; 964,444; 1,069,517; 1,507,890; and 1,959,736.
While spiral separators have been heretofore developed and used, such systems have not been completely successful and further improvements have been needed. In my copending U.S. application, Ser. No. 736,257, filed Oct. 27, 1976, and entitled "Adjustable Unit for Spiral Separators," now U.S. Pat. No. 4,146,137, issued Mar. 27, 1979 I have set forth one such improvement for a spiral separator wherein an attachment is added to enhance separator operation.
Spiral seed separators now known and utilized have still other disadvantages including, for example, a capacity limitation arising from the number of individual spirals that can be utilized due to the manner of introducing material to be separated into the device at the upper flights and the manner of discharging the fractions from the device after separation, the difficulty or complete absence of spiral adjustment needed to achieve better and more precise separation, and excessive noise problems.